Actuator latch mechanism



May 17, 1960 L. J. GIRARDIN 2,936,995

ACTUATOR LATCH MECHANISM Filed March 27. 1958 /NVENTOR LEON J GIRARD/N ATTORNEY ftion'of a pair /ofpilt valves. vlated by 'a manually in du'ced movememrand the,v second Apilot valves translated by -a-fluii pressure 'introduced thereto upon: translation of Lthe rs'tipilofvalve Thelatch mech'a'm'sm 'of this invention Vcontrols'trans- 'lation of thefsec'ond `pilot valve. It permits'the vsecond pilot yvalve to be translated. initially in response to the c Another object of 'sacrificing 'any jof the ori latch"'rnechanis'm of this invention.

,Uedists 2 Paten-t 2,936,995 y TTO ITHMECMHANM i' ISv Leon J. Girardin, Tarilvill, 44Conn., lassg'nor to United Aircraft Corporation, East Hartford, Conn., 4a corporavtion of Delaware Application Maren 27, 1958, seria-1 No. 724,415 4 claims. (c1. 2st-49) system. Y y f In the fuel system for which this invention is intended the 1niet,shut-'olf :valve is spring loaded 'closed and, further, it Ais''"pr'eSsufrized closed by a 'fluid pressure. When fliel 'ilow'to 'the power plant is 'desired the pressure yfluid 'Behind `the shut-oivlve is vented through 'the transla- The first valve is ztransiipueaun' of 'duid "pressure Kte one 'end of the upilot 'valve to its original postionla'nd `cutoi`the uid"pressure to the seeond'pilot valve. vlFu'rt-li'e'igit prevents the An vobject of this invention is tofprfo'vide vanirnproved l `lal:chntechanism to automatically control translation of ai pilot valve. y

the invention 'is' ton provide Iposi-tive ICC .is'pesidenedte .the left in bere sz against ena VV44 5f the bore. The lpilot valve is translated to thepo'siton shown when it is desired to open valve 12.

Cam 42 rotates about an axis at a right angleto kthe airisof pilot valve 30. The cam is rotated by reversible electr-tic motor 4`6 through gear 48 which meshes with gear VsegmentSll integrally connected with the cam. 'lf-he electric motor is part of an electric circuit 52 which ifncludes switch 54. One position of the switch operates the motor to'rotate cam 42 in a counter-clockwise direction and translate pilot valve 30 to the right, while another position o'f the switch operates the motor to rotate thec'am `in a clockwise ydirection and translate theA pilot valve tothe left.

Second pilot S6 'is located'within bore 58 in the casing. The pilot valve includeslands 60-an`d62 ,on Aits Vleft end 4and beveled shoulders 64 land 66 on its r'right end. Spring v68 -is mounted between the right end of Qthe'pilot 'valve and wall 70 Yof chamber 72 andloads the` pilot valvegto thefle'ft against end`7.4 of`bo're 58. Y

'Latch mechanism '7.6 rotates about Apivot `78 andlthrough contact with beveled shoulder 64 on Vpilot valve JSticontrols translation of the pilot valve. The latch meenanism consists of follower 8.0 and pawl 8 2. Spring 384 .urgeszthelatch mechanism in a counter-clockwise direction lto maintain Afollower `8l) in contactwith the l,perimany .intermediate portion'of bore 58 andpassage 96.con

'operationof a ltchlniechanis'm'cfor a rpilot valvewithout tem in whichthe pilotvalve functions.

inal requirements 'of they sys,-

Referring te thedrawing in derai 1 19is-afragmemary .portion of affuel control casing. zThe control includes {shut-ofi?r valve S12 'controlling-'the vadmission ofY metered fuelA from. passage 14'to'ma`nifold ,16 and the power plant, `1;go t`sh'own.` The valve`is'11`rgedto theleft against seat 11:8 byf'spfring 20 'in`cl1r`f1ber 22. Fluid jis admitted to "chamber'22 "tof aid in cltjsingv the fval",ve,"the uid being vadrrt-ted "through branch' p aSS'g 24U-from 'passage l26.

Bleed restriction 28"is'in"pa`ssage"26 immediately upstream of the connection with branchpassage 24.

First zpilot valve"30 -islocated Within bore 32 in casing 10. Thefpilotvalve'lhas lands34g`and 36 on anV intermediate' portion thereof and apair of shoulders 38 on fitsrigh-tfend. ""The Vshouldersmdeine a.-yoke engaging pin 440 which'is'eccent'rically connctdto cam J42. 'When no fuel is owing to the power plant, pilot valve 30 sun anefherebjeet eff Yin v'en on'is/-fa'prevgdeia p1! vlot valve I atching 'mechanism `having1the necessary reeter of cam T42.V vThe cam perimeter is defined `by a substantially circular section 86 and a flat section88.

As shown, 'follower 80 Yis againstflat sectionf88 so that fpawl v82'isr in its extended or eiectiveposition. Whenthe Ycam has been yrotated :so that follower 80 contacts ,circularsectionl'o thelateh mechanism is retracted, vthatv is rotated lin a clocli-wise directionfrom the .positionzshowm Y so that]r the .pawl is elevated above shoulderf64. Pilot valve" S6 v'thenlmay be .translatedjwithout interference between 'the pawl and. the'should'er.-

Passage 90 isrconnected toA an intermediate portion V of bore `32to supply a iluid pressure thereto. Passagel connects thesame portion' of the bore V,with chamber 94 'atfthe left end of bore 58.V Passagef26 lisconnected [to nects the `same portion .of the bore with chamber QS atl'thefleft end of bore 32. Hole l110 extends through ,pilot valve 130l and yprovides communication between Passage 11-2I ':onnec'tsv f chamberA i12-,toa suitable drain.

companying idrawing'whichillustrates an'emb'odiment of 'foperajron -f Y. v Prion-to 'the-opening of shut-off valve 12, vthe staterf thefuel `system and k:thevposition of the various control elemeritsfis as'follows. yFuel'is in passage 14, -butfthe 'force 4of spring '20 as well as the pressure of thenuid f l Vin chambenZZ, lvvhichmaybe that of the; fuel in passage I'14,"1h'olds the valve closed. YPilot valves .30 and -56 are each'in a position to the leftcin their respective bores, and cani42`is in a rotationalposi-tion such `thatfollower l8 0is`incontact with circularsection 86 Yandpavvl782- is raised.

In! the statedposition offpilotfvalvet) land 36 blocks 'the l entrance topassage 92andthe uidpressure admit- -t ed toibo re 32 bypassage 90 ,is .dead-.ended in. groove 71:1 4be`tween'lands'34 Vand'lands' 36. lIn vthe statedlposition ofpilot valvek56 land 62 blocks f the entrancefof passage 26 .to bore`58 to prevent theeadmissionof uid pressure tothe bore. 1 To open shutfol valve 12, switch 54 isY closed togactuate'motor 46 `arrdJrotate cam l42vis in a rcounterfclocl- Wisejdirection. Thececcentric pinfand yoke connection v `of. `caml 42rwithrpilotrvalvef() will cause theV pilotvvalve Itombe"translated to the right, opening passage 92 and permitting the introduction of fluid pressure from passage'90 and groove 114 to chamber 94 at the left end "86 on' the cam and the latch mechanism is retracted.

As pilot valve 56 is translated to the right, land 62 moves-away from passage 26 to connect the passage and groove 116 between lands 60 and 62. This connection unloads shut-off valve 12, the pressure Vin chamber 22 being vented through branch passage 24, passage 26, groove 116, passage 96, chamber 98, hole 110, chamber 72 and drain passage 112. The pressure in chamber 22 thus is reduced so that the pressure in passage 14 will open Valve 12 and fuel will flow through passage 16.

The above described events transpire as soon as communication is afforded by the movement of pilot valve 30 between groove 114and passage 92. As counterclockwise rotation of cam 42 and the resulting translation to the right of pilot valve 30 continues, follower 80 engages flat section 80 on the cam with the result that latch mechanism 76 drops to the position shown. Rotation of the cam and translation of the pilot valves is terminated when the elements are in the position shown in the drawing. The latch mechanism then is in its effective position.

Latch mechanism 76 affords a fail-safe provision in that in the event of a reduction of pressure ,in chamber 94, either intentionally or through malfunctioning of the system, shut-off valve 12 will be forced closed and cannot be reopened until the reason for the failure is determined. This provision is particularly important in an afterburner fuel system in which operation is intermittent and the power plant operator must be able to terminate operation or should be prevented from initiating operation. lFor example, if a failure inthe electrical system Voccurs after pilot valve 30 has been translated to the right, motor 46V could not be actuated to rotate cam 42 and translate thepilot valve to the left to cut of the admission of uid pressure to chamber 94. However, the

fluid pressure in passage 90 could be reduced intentionally so that the vforce of spring 68 would exceed the pressure in chamber 94 and pilot valve 56 would be forced to the left. Land 62 then would close passage 26 and permit a pressure build up in chamber 22 lto close shutoff valve 12. Further, if for some reason the fluid pressure in passage90 should drop off, the consequent reduction of the pressure in chamber 94 would result in pilot valve 56 being moved tothe left.,l

The shape of pawl 82 and that of shoulder 64 permits pilot valve 56 to be moved tothe left when the latch mechanism is extended and whenthe fiuid pressure in chamber 94 is reduced below the loading of spring 68.

As soon as shoulder 64 has been moved to the left past pawl 82, the pawl drops down into the groove between shoulders 64 and 66. As long as follower 80 remains in contact with at section 88, which will be as long as electric motor 46 is inoperative to restore cam 42 and pilot valve 30 to their original position, interference between the vertical face of pawl 82 and the vertical. face of shoulder 64 will prevent pilot valve 56 from being translated to the right to permit shut-off valve 12 to be opened.

If operation of the fuel system has been normal, and the'various elements are in the position shown in the drawing, shut-ofi valve 1,2 is closed and fuel flow is terminated by actuation of switch 54. The switch ismoved to a position which will operate motor 46 and rotate cam 42 in a clockwise direction. This movement raises latch mechanism 76 and translatespilot valve 30 to the left. Land 36 on the pilot valve will cut off uid pressure to chamber 94 at the left of pilot valve.56 and vent the chamber by the connection of passage 92 with chamber 72 and drain passage 11.2. As the pressurein chaml ber 94 diminishes spring 68 will translate pilot valve 56 to its original position at the left.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim: Y

l. A fuel control including rstY valve means, means for actuating said first valve means, second valve means having translational movement, means controlled by actuation of said first valve means for admittting uidpressure to said second valve means, said pressure `tending to translate said second Valve means in one direction, means acting upon said second valve means and tending to translate said second valve means in theopposite direction, cam means operatively connected with said first valve means and positioned in accordance with actuation of said first valve means, means actuated by said cam means for controlling movement of said second valve means in said one direction, and means for inactivating said cam actuated means when said second valve means moves in said opposite direction.

2. A fuel control including valve means, manually actuated means for translating said valve means, a pilot valve, means controlled byv translation of said valve means for admitting uid pressure to one end of said pilot valve, said pilot valve being translated in one direction by said pressure, resilient means loading said pilot valve in the opposite direction, cam means operatively connected with said valve means and positioned in accordance with movemen-t of said valve means, and latchmeans positioned by said cam for controlling movement of vsaid pilot valve.

3. A fuel control including a first pilot valve, manually actuated means for translating Vsaid pilot valve, a second pilot valve including a shoulder, means controlled by translation'of said first pilot valve for admitting fiuid pressure to one 'end of said second pilot valve, said second pilot valve being translated in one direction by said pressure, resilient means loading `said second pilot valve in the opposite direction, cam means operatively connected with said first pilot valve and positioned in accordance with movement of said first pilot valve, latch means positioned by said cam for controlling movement of said second pilot valve, said latch means including a pawl cooperating with said second pilot valve shoulder, a portion of said pawl and a cooperating portion of said shoulder being contoured tomove said pawl to a non-controlling position in response to translation of said second pilot valve in said opposite direction.

'4. A fuel control including a first pilot valve, cam means operatively connected with said pilot valve, means for coordinately translating said pilot valve and rotating said cam meansfrorn a first position .to a second position and return, a second pilot valve including shoulder means,

resilient means loading said second pilot valve in an initial position, means controlled by translation .ofY said Yrst pilot valve to' said second position ,for admitting fluid pressure to'one end of 4said second pilot valve to translate said second pilot valve to` a displaced position, latch means including a follower riding on said cam means and a pawl for cooperating with said second pilot valve shoulder means, said cammeans being contoured to retract said latch means when saidi'irst pilot valve and said cam means are in said first position and to extend saidV latch means so that said pawl may engage Vsaid shoulder,Y means whenr said first pilot valve and said cam References Cited in the file of this patent Y UNITED STATES PATENTS 

